LSQC: Low scaling quantum chemistry program

Abstract

LSQC is a low scaling quantum chemistry program for ab initio and DFT calculations of large systems. This program includes two methods, generalized energy-based fragmentation (GEBF) approach and cluster-in-molecule (CIM) approach. In the GEBF approach, the energy and properties of a large system can be obtained from the calculations of a series of subsystems. In the CIM approach, the electron correlation energy can be obtained from various clusters based on localized molecular orbitals. A low scaling quantum chemistry program, called LSQC, is described in this article. This version includes two linear scaling methods, generalized energy-based fragmentation (GEBF) approach and cluster-in-molecule (CIM) approach. In the GEBF approach, a variety of electron structure methods (including ab initio and density functional theory) are available for the calculations of ground-state energies, geometry optimizations, vibrational spectra, and other molecular properties for large systems. In the CIM approach, the electron correlation energies of large systems can be approximately obtained at the second-order Møller-Plesset perturbation theory and couple cluster levels. In this article, the details and the capabilities of the LSQC program are presented.